go/analysis/analysistest: accept comments of /* */ form

Testing on analysis of location of comments, or lack of comments may
need /* */-style comments to avoid interfere with the tested code.

Change-Id: Id190aa243dc8ca90808c58f6d5dd4db1ade9f1c4
Reviewed-on: https://go-review.googlesource.com/c/tools/+/212636
Reviewed-by: Michael Matloob <matloob@golang.org>

go/analysis/analysistest/analysistest.go

@@ -193,11 +193,13 @@ func check(t Testing, gopath string, pass *analysis.Pass, diagnostics []analysis
 			for _, c := range cgroup.List {
 
 				text := strings.TrimPrefix(c.Text, "//")
-				if text == c.Text {
-					continue // not a //-comment
+				if text == c.Text { // not a //-comment.
+					text = strings.TrimPrefix(text, "/*")
+					text = strings.TrimSuffix(text, "*/")
 				}
 
 				// Hack: treat a comment of the form "//...// want..."
+				// or "/*...// want... */
 				// as if it starts at 'want'.
 				// This allows us to add comments on comments,
 				// as required when testing the buildtag analyzer.

go/analysis/analysistest/analysistest_test.go

@@ -54,6 +54,15 @@ func main() {
 	// OK
 	println("hello, world") // want "call of println"
 
+	// OK /* */-form.
+	println("안녕, 세계") /* want "call of println" */
+
+	// OK  (nested comment)
+	println("Γειά σου, Κόσμε") // some comment // want "call of println"
+
+	// OK (nested comment in /**/)
+	println("你好，世界") /* some comment // want "call of println" */
+
 	// OK (multiple expectations on same line)
 	println(); println() // want "call of println(...)" "call of println(...)"
 }